Crazy ... but faulty analogy The idea of allowing spammers to "buypass" ISPs spamfilters is disgraceful. If Television stations are willing to accept "infomercials" for such wonderfully physiologically impossibilities like the products that are "guaranteed to enlarge that certain part of the mail anatomy", then you can be sure that ISPs will happily accept money for letting spam for these products through as well.
The analogy presented is flawed though ... It makes the assumption that any mail that is tagged by the filter as "Spam" will be automatically trashed and sets that up as a straw man that implies this to be the fault of goodmail. The reality is that even without goodmail, if the mail from say your doctor looks like spam, then it's going to be tagged as such today and dealt with by whatever rules you or your ISP uses now.
Goodmail doesn't change your ISP's current mail handling except to allow spammers to buy a "pink slip contract" whitelisting their mail. If you or your ISP junk spam unseen today, it won't change with goodmail.